1. Field of the Invention
The present invention relates generally to a self-emitting display apparatus, and more particularly to a self-emitting display apparatus having a plurality of kinds of self-emitting devices and being capable of displaying color images.
2. Description of the Related Art
Recently, organic electroluminescence (EL) display apparatuses have widely been developed as self-emitting display apparatuses which can achieve quicker response and provide a wider angle of view field than liquid crystal display apparatuses. The organic EL display apparatus comprises a plurality of organic EL display devices each having a switching element. Each organic EL display device (hereinafter referred to as “display device”) is constructed such that a light-emission layer serving as an optical modulation layer is interposed between a pair of electrodes.
The organic EL display apparatus that displays a color image comprises light-emission layers that emit different color light associated with each display device. For example, the light-emission layers of the respective display devices are formed of luminous materials associated with red (R), green (G) and blue (B). The red, green and blue luminous materials, of which the light-emission layers are formed, have different light-emission characteristics associated with the respective colors.
In particular, in the case of typical high-molecular weight organic EL materials, which have been used in recent developments, when a current density (i.e. a value obtained by dividing a current applied to the device by a light-emission area) is equal in the red, green and blue display devices, the luminance half-value period (i.e. the period within which the luminance of the display device decreases to ½) of the blue display device is shortest. Since the degradation of the blue display device is earlier than the other color display devices, that is, the red and green display devices, the white balance will be lost with the passing of time. If the loss of white balance is conspicuous, a white image, when displayed, may have a yellowish component.
In order to maintain a constant white balance in a display apparatus wherein the respective color display devices have equal areas, it is necessary to control the current amount for each color. However, if the current amount for the blue display device is decreased, the luminance lowers and the display quality will considerably deteriorate.